Text to text applications include machine translation, automated summarization, question answering, and other similar applications where a machine carries out the function of understanding some kind of input information, and generating text. The input information is often “text”, but more generally, can be any kind of information that is received and understandable by the machine.
Conventional text to text applications use heterogeneous methods for implementing the generation phase. Machine translation often produces sentences using application-specific decoders that are based on work that was conducted on speech recognition. Automated summarization produces abstracts using task specific strategies.
Machine translation systems rely on training that is carried out based on corresponding, or “parallel” information that exists in both of two languages. The information in the two languages can be from many sources. Sometimes, it is known that the contents of two documents represent the same information.
The internet is a source of information. Documents on the Internet are often available in multiple different languages. However, it may be difficult to identify mutual translations within the many different web pages on the Internet. Comparing all documents within the document pool using conventional systems would require a number of computations that scales with the square of the number of document pairs.
For example, each English language page can be compared with every known French language page, to determine the best match. This naive system would take extreme computation times to identify the training pairs.
Philip Resnik has suggested a method which identifies parallel documents by producing pairs of similar URLs which are presumed to be in different languages. For example, if one URL says “En”, and another URL is similar but differs only by stating “FR”, then these are presumed to be parallel URLs.
Not all Web documents are in this form, and Resnik's system is quite specific to web pages which have that specific kinds of URLs.